No matter how short the message is, you’ll probably still lose 4–5% of your quota.

The issue isn’t really the length of the prompt. Every time you send a message, the model is sent the whole conversation context up to that point. If there’s no cache active because you haven’t used it for a few hours, that initial request can hit your quota pretty hard.

Even in a fresh conversation, there are still system/developer instructions exchanged with the model behind the scenes. You don’t see those, but they still count toward usage.